AU2007249142B2 - An improved Z section structural member - Google Patents

Abstract

l1 The present invention relates to Z shaped structural members configured so that they are structurally robust by having lips and lip returns, and other structural features, but do not suffer the same drawbacks as known structural members of this 5 type in that the flange portions include nestable longitudinal stiffening recesses, which increase the bending strength of the purlin, and allow for traditional purlin widths to be used. 2 8 -14 10a '27 Fig 1

Description

13726AU ORIGINAL Complete Specification Applicant: Fielders Australia Pty Ltd Title: An improved Z section structural member Address for Service: LESICAR PERRIN, 49 Wright Street, Adelaide, South Australia 5000, Australia The following statement is a full description of this invention, including the best method of performing it known to me/us: 2 It is therefore an object of the present invention to overcome some of the aforementioned problems or at least provide the public with a useful alternative. It is a further object of the present invention to provide a Z section structural member having upper and lower flange portions of predetermined width terminating 5 in lip returns, the flange portions having longitudinal recesses to facilitate nestling with further structural members, and to provide the strength required to prevent bending of the flange portions. SUMMARY OF THE INVENTION Therefore in one form of the invention there is proposed an elongate structural 10 member including: a substantially vertical web portion; two oppositely directed flanges projecting outwardly from upper and lower ends of the vertical web portion, whereby one of said flanges extends a shorter distance from the web portion than the other flange to allow for nesting of two inverted structural 1 5 members; and wherein the vertical web portion includes at least one recess extending along a portion of the height of the web portion, each recess being positioned and configured such that when a first structural member is inverted and nested inside a second structural member, the recesses form a hollow channel therebetween which extends the length 20 of the nested members, and wherein each of said flanges include lips at ends thereof and a stiffening recess, each of said stiffening recesses being equidistant from said web portion and configured such that the stiffening recesses of two inverted nesting structural members nest inside one another. The flange stiffening recesses allows for the structural member to have a wider 25 flange component with greater bending strength characteristics. Preferably the lip of an upper flange extends perpendicularly downwardly and the lip of a lower flange extends perpendicularly upwardly. In a first embodiment each lip terminates in a substantially C shaped projection directed towards the web portion, providing the structural member with 30 additional bending strength properties.

3 In a second embodiment the lip of the upper flange terminates in a substantially C shaped projection directed towards the web portion and the lip of the lower flange terminates in a perpendicular lip return also directed towards the web portion. 5 In a still further embodiment the lip of the upper flange extends downwardly at an angle between 90 and 180 degrees from the upper flange, and the lip of the lower flange extends upwardly at an angle between 90 and 180 degrees from the lower flange. Preferably the lip of the upper flange extends downwardly at angle of 10 approximately 100 degrees from the upper flange, and the lip of the lower flange extends perpendicularly upwardly from the lower flange. In preference the upper lip terminates in a perpendicular lip return directed towards the web portion, and the lower lip terminates in a perpendicular lip return also directed towards the web portion. 15 Preferably said web portion includes a main stiffening recess located centrally along the web portion and secondary recesses disposed between the main recess and upper and lower ends of the web portion respectively, each secondary recess being equidistant from the ends of the web portion and the recesses being configured such that when two inverted structural members are nested, the central and two secondary 20 recesses form three channels along the length of the assembled members. Advantageously said structural member is an extruded length of cold roll formed steel. In a further form of the invention there is proposed a structural assembly including two inverted and nesting structural members as defined above. 25 BRIEF DESCRIPTION OF THE DRAWINGS The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings: 4 Figure 1 illustrates a cross sectional view of a Z section structural member in accordance with a first embodiment of the present invention; Figure 2 illustrates a cross sectional view of a Z section structural 5 member in accordance with a second embodiment of the present invention; Figure 3 illustrates a cross sectional view of a Z section structural member in accordance with a third embodiment of the present invention.

5 DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described 5 without departing from the spirit and scope of the invention. Figures 1-3 show, in cross section, purlin or roof system structural members 10a, 10b and 10c in accordance with the present invention. The purlins are preferably cold formed from roll reduced steel to form a Z shape. Each embodiment shares certain common features and so these will only be described once and be referred to 10 using like reference numerals. The structural member I Oa includes a substantially central web 12 with two oppositely directed parallel flanges or flange portions 14 and 16. The flanges 14 and 16 extend outwardly and substantially perpendicularly from the ends of the central web 12. Flange 16 is adapted to be narrower than flange 14 to thereby be able to 15 accommodate flange 14 when two purlins I Oa are nestled together to form a longer beam. As an example, flange portion 14 would typically be 95.5mm while flange portion 16 would be 98.5mm, allowing at least a few millimetres to accommodate the flange 14 of a further purlin. A typical height such purlins is 300mm. Those skilled in 20 the art would realise that in order for this to work, every second purlin in a plurality of nestled purlins forming a continuous beam needs to be inverted. In addition, the upper and lower flanges 14 and 16 of the purlin 1 Oa have a lip 18 and 20 respectively, extending from the ends of each flange. In this first embodiment, the upper and lower lips 18 and 20 project substantially perpendicularly 25 from their respective flange portions and terminate in a curved lip projection 22 and 24. The curved lip projections 22 and 24 each form a substantially C shaped channel, with the upper projection 22 having a recess directed towards the central web 12, and the lower projection 24 having a recess directed away from the central web 12. Those skilled in the art would realise that when one purlin 1Oa is nestled 30 within another purlin 10a, the adjacent lip projections of respective purlins do not 6 contact or interfere with one other, in fact, they are spaced apart and face each other. The lip projections serve to provide additional strength to the purlin as mentioned in the preamble of the invention. The purlin 10a also includes a number of strengthening recesses. For example, 5 in order to strengthen the central web and allow for a long structural members, there are two recesses 26 present at an upper and lower position, and a central larger recess 27 therebetween. The upper and lower central web recesses 26 are positioned so that they are equidistant from the respective flange portions. Those skilled in the art would realise that when two purlins are nestled together, as described above, the recesses 26 10 of each purlin face each other and form a longitudinally extending tunnel between central webs. Longitudinally extending stiffening recesses 28 are also located on the upper and lower flange components 14 and 16 respectively. These stiffening recesses 28 are essentially what allow the purlins of the present invention to have a convention width 15 because they add bending strength by stiffening the flange members 14 and 16. The way the recessed interact with the stiffening members of adjoining purlins is also important in enabling the purlins to be generally wider than hitherto known purlins having lip components. The stiffening recesses 28 are equidistant from the central web 12 and 20 dimensioned to allow the recess of the narrower flange 14 to be nestled within the recess 28 of flange 16. The dimensions of the longitudinal flange recesses 28 are chosen accordingly. Figure 2 shows a Z sectioned purlin I Ob of an alternative embodiment. This embodiment shares many common features to the first embodiment shown in Figure 25 1. The common features include the central web 12 containing longitudinally extending recesses 26 and 27 providing additional web strength. The member lOb also includes upper and lower flanges 14 and 16. The flanges project outwards from the central web 12 in opposing directions and include the same stiffening recesses 28 described above, allowing for the nestling of inverted purlins. 30 Member 10b also includes perpendicular projecting upper and lower lip components 7 18 and 20, with the upper lip 18 component terminating in a C shaped lip projection 22 as per the first embodiment. The difference lies in the configuration of the lower lip 20 which includes a lip return 30 extending perpendicularly from the lip 20 and directed towards the central 5 web 12. Both the curved lip portion 22 and the lip return are directed towards the central webbing for greater ease of insertion and removal of two overlapping Z sectioned purlins I Ob. Finally, Figure 3 shows a third embodiment of the present invention in the form of Z sectioned structural member 10c. This purlin shares common features with 10 the first two embodiments shown in Figures 1 and 2. Again, the common features shared by this third embodiment include the central web 12 having longitudinally extending recesses 26 and 27, and upper and lower flanges 14 and 16 having stiffening recesses 28. To further facilitate overlapping, purlin 10c includes a lower lip 20 extending perpendicularly from the lower flange 16 and terminating in a 15 perpendicular lip component 30 as per the second embodiment. However the top flange portion includes a lip component 32 projecting angularly from the top flange 14. The projection angle is typically, but is not intended to be limited to, approximately 100 degrees from the lower surface of the upper flange 14. The lip allows for more efficient insertion and removal of overlapping purlins 1 Oc. 20 The skilled addressee would now appreciate the benefits of the present invention. The Z shaped structural members embodied herein are configured so that they are structurally robust by having lip returns and other structural components, but do not suffer the same drawbacks as known structural members of this type in that the flange portions include nestable longitudinal stiffening recesses, which increase the 25 bending strength of the purlin, and allow for traditional purlin widths to be used. Further advantages and improvements may very well be made to the present invention without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope 30 and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus. In any claims that follow and in the summary of the invention, except where the context requires otherwise due to express language or necessary implication, the 5 word "comprising" is used in the sense of "including", i.e. the features specified may be associated with further features in various embodiments of the invention.

Claims (14)

1. An elongate structural member including: a substantially vertical web portion; 5 two oppositely directed flanges projecting outwardly from upper and lower ends of the vertical web portion, whereby one of said flanges extends a shorter distance from the web portion than the other flange to allow for nesting of two inverted structural members; and wherein the vertical web portion includes at least one recess extending along a 10 portion of the height of the web portion, each recess being positioned and configured such that when a first structural member is inverted and nested inside a second structural member, the recesses form a hollow channel therebetween which extends the length of the nested members, and wherein each of said flanges include lips at ends thereof and a stiffening recess, each of 15 said stiffening recesses being equidistant from said web portion and configured such that the stiffening recesses of two inverted nesting structural members nest inside one another.

2. An elongate structural member as in claim 1 wherein the lip of an upper flange extends perpendicularly downwardly and the lip of a lower flange extends 20 perpendicularly upwardly.

3. An elongate structural member as in claim 2 wherein each lip terminates in a substantially C shaped projection directed towards the web portion, providing the structural member with additional bending strength properties.

4. An elongate structural member as in claim 3 wherein the lip of the upper 25 flange terminates in a substantially C shaped projection directed towards the web portion and the lip of the lower flange terminates in a perpendicular lip return also directed towards the web portion.

5. An elongate structural member as in claim 1 wherein the lip of the upper flange extends downwardly at an angle between 90 and 180 degrees from the 30 upper flange, and the lip of the lower flange extends upwardly at an angle between 90 and 180 degrees from the lower flange. 10

6. An elongate structural member as in claim 5 wherein the lip of the upper flange extends downwardly at angle of approximately 100 degrees from the upper flange, and the lip of the lower flange extends perpendicularly upwardly from the lower flange. 5

7. An elongate structural member as in claim 6 wherein the upper lip terminates in a perpendicular lip return directed towards the web portion, and the lower lip terminates in a perpendicular lip return also directed towards the web portion.

8. An elongate structural member as in any one of the above claims wherein said 10 web portion includes a main stiffening recess located centrally along the web portion and secondary recesses disposed between the main recess and upper and lower ends of the web portion respectively, each secondary recess being equidistant from the ends of the web portion and the recesses being configured such that when two inverted structural members are nested, the central and two 15 secondary recesses form three channels along the length of the assembled members.

9. An elongate structural member as in any one of the above claims wherein said structural member is an extruded length of cold roll formed steel.

10. A structural assembly including two inverted and nesting structural members 20 as defined in any one of claims 1-9.

11. An elongate structural member according to any one of claims 1-9 and substantially as hereinbefore described with reference to Figure 1.

12. An elongate structural member according to any one of claims 1-9 and substantially as hereinbefore described with reference to Figure 2. 25

13. An elongate structural member according to any one of claims 1-9 and substantially as hereinbefore described with reference to Figure 3.

14. An elongate structural member according to claim 10, substantially as hereinbefore described with reference to the accompanying figures.